The present invention relates to a loading station for plate elements. The invention also relates to a machine for processing these elements incorporating such a loading station.
A processing machine, for example a printing machine, is used notably in the packaging industry, for example for making cardboard boxes from plate elements such as sheets of cardboard.
The processing machine usually comprises several stations or workstations, each intended to carry out a specific operation. The plate elements are fed at the inlet of the machine by the feeding station or infeed station or feeder installed upstream. These plate elements are recovered at the outlet of the machine in the delivery station downstream in the form of processed elements, blanks or boxes ready for use.
The feeder automatically introduces the elements into the machine one after another. The feeder first of all comprises a lower vacuum conveyor, which sends the elements into the machine successively one after the other. At this level, the elements are clearly separated and do not overlap in the form of a stream. The elements are then driven and processed one after the other in the machine.
Upstream of the conveyor, a batch of stacked vertical elements is placed in the feeder. The feeder also comprises a vertical gauge. The gauge is used for the frontal alignment of the elements. This gauge is also used for extracting the elements one after another from the bottom of the batch. The gauge can also move vertically, so as to adjust the gap beneath the nose of the gauge, depending on the thickness of the elements.
A first drawback is that the batch applies a considerable pressure force, mainly on the element at the bottom of the batch placed on the conveyor. This pressure is all the greater if the cardboard has a high grammage and the batch is high. This pressure tends to squash these bottom elements that follow one another and to apply a stress, disrupting the conveying of the element by the feeder, reducing the quality of the infeed and consequently the sending of the elements into the machine. In certain cases, the register of the fed elements is lost. In other cases, the feeder feeds in two elements at the same time instead of just one, which is undesirable.
Such a pressure also increases the friction between the element at the bottom of the pile and the element immediately above with which it is in contact, when the bottom element is sent. Since the surfaces may be preprinted or coated with a layer, for example of white color or of other colors, they will be damaged by marks.
In order to feed a machine, an operator continually places small batches of stacked elements in the infeed station. The operator picks up and carries these batches by hand. This makes the work of the operator particularly tiresome, for example when processing corrugated cardboard sheets of large dimensions. Moreover, such manual loading limits capacity in terms of processing speeds.